日本近海のイカ肝臓中の水銀の定量と成熟に伴う水銀濃度の変化

抄録

It is known that heavy metal, such as cadmium (Cd), is concentrated in the digestive gland of Japanese common squid (Todarodes pacificus). Mercury is also a harmful metal, but its distribution in squid and cuttlefish (Sepia madokai) has been scarcely reported in the East China Sea. In this report, determinations of mercury in the digestive glands of squid and cuttlefish were made by ICP-MS. In order to perform the quantitative analysis of mercury by ICP-MS, samples of squid and cuttlefish were taken in the same area of the East China Sea in 2012. Their digestive glands were removed and freeze-dried at −60°C, for 24 h. Then, to this was added 5 mL of a tetra methyl ammonium hydroxide solution and 30 μg of a gold solution, and heated with a drying machine at 80°C for 12 h. The results obtained by this method shows almost the same detection limit as the conventional method, such as cold-vapor atomic-absorption spectrometry. The measured values, such as DORM-1, DOLT-2 and NIES-13, by this method were almost the same as the certified values within 96–110%. The parameters, mantle length and gonad-somatic index (GSI), were used for the maturation of squid and cuttlefish. The concentrations of mercury in the digestive glands of T. pacificus and S. madokai were low, and almost constant, although they were maturing. This indicates that the biological half-life of Hg in the digestive glands were not as long as that of Cd.